Adds base cache module and class #17
Adds most of archive methods and invoke archive tasks #18
delete MD archive module #18
remove s3 module
add slugify function
add partial work on updated models
add slugify function in text.py module
add property for absolute path to to state cache dir
more partial work on models
model updates #20
base datasource update
add _elec_slug method to md datasource
add StateCache to StateBase
replace cache_dir with cache.abspath on BaseFetcher
parial work on md loader. for discussion #23
base loader tweaks. #23
delete previously loaded results for md #23
tweak logging for md loader delete #23
Merge branch 'tasks' into dev